Liquid chromatographic (LC) techniques with electrochemical detection, which provide extreme sensitivity, will be used to study relationships of the catecholamines neurotransmitters and ascorbate in small animal brain systems. The LC techniques are also to be especially applied to in vitro release studies of catecholamines from brain sliced and synaptosomes. A modification of the LC technique, called flow injection analysis, in which samples are analyzed by direct electrochemical detection will be applied to release studies. In the in vivo electrode work, we now plan a serious move toward smaller, more reliable electrodes. The emphasis will be more on quantitative measurements with the in vivo electrodes. In addition, we are now investigating electrode responses in new brain areas, previously unexamined, particularly detection of sensory inputs with electrochemical electrodes in thalamic areas.